Yoon Park

Seo Si-won

Go Yo-han: a misguided problematic probation officer who protects and observes Ro-woom.

Bang Jeong-seok

Han Ki-joon, Jin Ha-kyung's ex fiance

Manager Bae Soo-jin

Chae Joon/Dr. Ian Chase Choi Min-young as Young Chae Joon

Kim Do-yoon, Hyun-jin's handsome younger husband, CEO of an up-and-coming app development startup company.

Song Min-gyu

Moon Tae-rang

Lord Kiseong (Episode 16)

Kang Ki-seok, an ace lawyer who is Tae-rim's rival. He is calm and gentle with a strong charisma.

Chu Young-bae

Lee Kang, the radio station's competent producing director. Because of his perfectionism, every program he handles achieved No. 1 in listener ratings.

Yoon Soo-soo

Kang Woo-il, the warm and confident, yet sensitive vice-chairman of Brain public relations firm. He is Hwan-ki's close friend and fiancé of Eun Yi-soo. Lee Tae-woo as young Kang Woo-il

Park Jae-wan (season 1; guest season 2)

Jung Ji-hoon

Seo Yoon-hoo

Park Jae-joon, younger step-brother of Min-joon and medical student

Cha Kang-jae

Kim In-seok

Kim Joon-sung

Lee Won-il

Woo Il-kyu, second-year resident

Kang Gun Lee Tae-woo as child Gun

Park Ho-gi